Is Robert Burton's Anatomy of Melancholy literature of the emotion?
I wouldn't call Burton's Anatomy of Melancholy the literature of emotion. It's more like a social or cultural digression about humanity and the social/psychological troubles humanity faced in his time (early 17th century). The melancholy refers to the general bewilderment or anxiety people have had to endure since the Biblical Fall. He discusses love, marriage, religion and it all becomes kind of a psychological treatise, giving ideas of how to cope with the melancholy of love and religion (fear of damnation in light of predestination - popular at that time) or the fact that this was the tail end of the Renaissance: the end of one era, moving on to the next with Newton (mid 17th century) and on to the Enlightenment (18th century).
In general, it is just a wide range of discussions on human melancholy by Burton, a guy who was as well read/learned of any of his time, so it can seem all over the place.